F450 vs F350 SRW payload

Grit dog wrote:

I'll say tires 100% have a substantial factor of safety built into their published load ratings.

You can buy the SAE standard if you really want, but essentially boils down to:

Tires are tested at their rated load, and not higher, for 1 hour at their rated speed, in a room heated to 100F. There is no additional safety factor required for validation. The safety factor is essentially up to the automakers, by specifying a tire load and/or speed rating that is higher than needed for the specified use. A tire manufacture may perform a Step Up Test beyond the target certification but this is not required, nor am I aware of it even being common. I supposed that some tires may be validated at a speeds and loads lower than ultimate failure, but this would place them in a sales disadvantage since tires will be selected by standardized ratings.

If you really think tire makers are over-designing tires, I suggest this read:
https://jalopnik.com/goodyear-knew-of-dangerous-rv-tire-failures-for-over-20-1824997252